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climatic variation and change

…as sudden climate fluctuations, called Dansgaard-Oeschger events, in which the temperature jumped 5° to 7° C (9° to 13° F), remained in that state for a few years to centuries, jumped back, and repeated the process several times before settling into the new state for a long time—perhaps 1,000 years.…

These Dansgaard-Oeschger (DO) cycles, recorded in both ice cores and marine sediments, occurred approximately every 1,500 years. A lower-frequency cycle, called the Bond cycle, is superimposed on the pattern of DO cycles; Bond cycles occurred every 3,000–8,000 years. Each Bond cycle is characterized by unusually cold…

The Dansgaard-Oeschger cycles of the last glacial period are now recognized as representing alternation between two climate states, with rapid transitions from one state to the other. A 200-year-long cooling event in the Northern Hemisphere approximately 8,200 years ago resulted from the rapid draining of glacial…